I think people are confuse on what mmo vs multiplayer is?

I don't totally understand MMO vs multiplayer vs co-op, I just know I don't want anyone else in my game. I think it could MAYBE be fun to have a dedicated neighborhood for other player-controlled content to appear, but it seems like, whatever the actual term is, things would be boring at best with the sims having connectivity to other people's games, and chaotic and hugely problematic at worst. Definitely prefer at least having the option to play entirely single-player.